THERMODYNAMIC SIMULATION OF IONIZATION EFFECTS IN INDUCTIVELY-COUPLEDPLASMA

Possible ionization effects on the analytical signal in mass spectrome try with a given high-temperature source are considered with the use o f the multicomponent quasi-stationary thermodynamic model suggested pr eviously for thermochemical processes in inductively coupled plasma. C hanges in the electron concentration in the analytical zone due to the presence of matrix elements with different ionization potentials have been calculated, and groups of elements have been distinguished that essentially differ in the efficiency of influence. Three-dimensional p lots of the electron concentration, the ratios between the partial pre ssures of matrix ions and electrons, and the degree of suppressing the ionization of analyte atoms with different ionization potentials have been constructed versus the temperature and the sodium concentration at various efficiencies of nebulization systems and various starting m olar ratios of water vapor and argon. The main trends in ionization ef fects have been revealed. Model plasma compositions have been calculat ed for various added concentrations of interfering elements with diffe rent ionization potentials (Na, Mg, I, Br, Cl). With regard to mass di scrimination in the mass analyzer, the possible degree of suppression of the signal of Co ions under these conditions have been calculated. On the basis of satisfactory agreement between experimental and theore tical results, a mode is recommended for the thermodynamic simulation of thermochemical processes in inductively coupled plasma.